Grilled Nectarine Summer Salad

Place onion slices in a medium nonreactive heatproof bowl. In a small saucepan, combine vinegar, ½ cup water, sugar, 1 teaspoon salt, and coriander seeds. Bring to a boil over medium-high heat; cook for 2 minutes, stirring occasionally. Remove from heat and pour over onion.

Let onion mixture cool at room temperature for 30 minutes; refrigerate until ready to use. (Can be made 1 day ahead and refrigerated in an airtight container.)

Spray a large cast-iron grill pan with cooking spray, and heat over medium-high heat. Working in batches, add nectarines; cook until grill marks form, about 2 minutes per side.

In a large bowl, toss together nectarines, arugula, strawberries, blueberries, and pecans until well combined. Using a slotted spoon or a fork, remove onion from pickling liquid, discarding any coriander seeds; add onion to salad. Strain and reserve pickling liquid; discard any solids.

In a small bowl, whisk together 2½ tablespoons reserved pickling liquid, mustard, garlic, and remaining ½ teaspoon salt. Gradually whisk in oil until well combined. Drizzle salad with desired amount of dressing, tossing until well combined. Serve immediately.